Published online by Cambridge University Press: 22 March 2016
Transition metal oxide thin film heterostructures have garnered increasingresearch interest in the last decade due to their multifunctional properties,such as ferromagnetism and ferroelectricity, which may be utilized in nextgeneration device applications. Many previous works reported on the depositionof such structures on oxide substrates such as SrTiO3, which are notcompatible with CMOS applications where Si(100) is the mainstay substratematerial. BiFeO3 (BFO) is a room temperature insulating ferroelectricand antiferromagnet, a well-known multiferroic material. SrRuO3 (SRO)is a ferromagnetic metal with the Curie temperature (TC) of 165K.Unexpected properties emerge when these two dissimilar materials are conjoined.However, there has been no report on exploring the magnetic properties of BFOwhen it is in contact with SRO, and particularly when they are integrated withSi(100) substrates, which is the subject of present study. BFO/SRO thin filmshave been epitaxially grown on Si (100) substrates by introducing MgO/TiNepitaxial buffer layers using pulsed laser deposition. BFO thin films show roomtemperature ferroelectricity as observed from piezo force microscopy (PFM)measurements. The magnetic data collected from BFO thin films show typicalantiferromagnetic features as expected. The TC of SRO in all thesamples studied was found be ∼ 170K, close to the reported value of165K. Interestingly, we have noticed that the coercive field of SRO layerincreased from 4 kOe to 15 kOe (nearly fourfold) by reducing its thickness from180 to 23nm, while keeping the thickness of BFO layer constant at 100nm. Pinningof Ru ions by ferroelectric domain walls in BFO, strong interfacial exchangecoupling and SRO layer thickness could cause the observed enhancement incoercivity. Our near future work will address the precise underlying mechanismsin greater detail.